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Titolo:
ADSORPTION OF CATIONIC AND ANIONIC SURFACTANTS ON METAL-OXIDE SURFACES - SURFACE-CHARGE ADJUSTMENT AND COMPETITION EFFECTS
Autore:
LEE EM; KOOPAL LK;
Indirizzi:
WAGENINGEN UNIV AGR,DEPT PHYS & COLLOID CHEM,DREYENPLEIN 6 6703 HB WAGENINGEN NETHERLANDS WAGENINGEN UNIV AGR,DEPT PHYS & COLLOID CHEM 6703 HB WAGENINGEN NETHERLANDS
Titolo Testata:
Journal of colloid and interface science
fascicolo: 2, volume: 177, anno: 1996,
pagine: 478 - 489
SICI:
0021-9797(1996)177:2<478:AOCAAS>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
FIELD LATTICE MODEL; IONIC SURFACTANTS; ADSORBED LAYER; STATISTICAL THERMODYNAMICS; ELECTROLYTE INTERFACE; ASSOCIATION COLLOIDS; (HYDR)OXIDES; TEMPERATURE; HEMATITE; RUTILE;
Keywords:
AD-MICELLES; ADSORPTION IN HEMI-MICELLES; ADSORPTION IN NONYL BENZENE SULFONATE; ADSORPTION DODECYL PYRIDINIUM CHLORIDE; ADSORPTION TETRADECYL PYRIDINIUM CHLORIDE; ADSORPTION RUTILE; ADSORPTION ON ADAPTATION; SURFACE CHARGE SURFACE CHARGE; ADJUSTMENT SURFACTANT; IONIC STRENGTH EFFECT ON ADSORPTION THEORY; SELFCONSISTENT FIELD (SCF) FOR ADSORPTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
23
Recensione:
Indirizzi per estratti:
Citazione:
E.M. Lee e L.K. Koopal, "ADSORPTION OF CATIONIC AND ANIONIC SURFACTANTS ON METAL-OXIDE SURFACES - SURFACE-CHARGE ADJUSTMENT AND COMPETITION EFFECTS", Journal of colloid and interface science, 177(2), 1996, pp. 478-489

Abstract

The adsorption of cationic and anionic surfactants on rutile is studied as a function of surfactant concentration and ionic strength in solution. The pH is kept constant for each series of isotherms. Special attention is given to the extent of adaptation of the surface charge asa function of surfactant adsorption. Experimental results are complemented with model calculations based on the self-consistent (mean) field lattice theory for adsorption and association (SCFA) to confirm the correctness of the given interpretation. The adsorption behavior of sodium nonyl benzene sulfonate (SNBS) and dodecyl or tetradecyl pyridinium chloride (DPC/TPC) on rutile is broadly similar. Isotherms can be divided in two regions by the (approximately) common intersection point(cip) between isotherms measured at different salt concentrations, Before the cip adsorption occurs head-on (hemi-micelles); after the cip both head-on and head-out adsorption( ad-micelles) occur. Intersectionpoints similar to the cip occur in the proton excess and the net surface charge/surfactant charge plots. Although broadly similar in their adsorption behavior, the SNBS and DPC/TPC systems differ markedly if the charge situation near the interface is considered. SNBS follows simple rules; the strongly adsorbing SNBS head groups can compete easily with the salt ions for the surface sites. The point where the surface charge and the surfactant charge balance, the equivalence point, and the cip in the isotherms coincide. Moreover, the cip corresponds with the isoelectric point (iep). The DPC and TPC systems behave in a more complicated way, due to their relatively weak interaction with the surface. The cip in the isotherms and the cip in the net surface/surfactant charge plots occur at much lower adsorption values than the equivalence point. Go-ions thus contribute at the cip to the charge balance inthe surface region, In this situation the iep will occur at lower adsorption values than the cip. (C) 1996 Academic Press, Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/07/20 alle ore 06:27:20